A warning to the nerd who dares mix his ballpoints with this pen! It's a dangerous life for a nerdlinger, now the University of Illinois has introduced a pen that writes electrical circuits in real silver.

The university team, led by professor Jennifer lewis and professor Jennifer Bernhard, published their findings in the science journal Advanced Materials, detailing that "pen-based printing allows one to construct electronic devices 'on the fly'."

Using the pen like an ordinary pen, the user "writes" the paper-mounted wires, with the ink leaving behind real silver that acts as conductive paths between components, such as LEDs. In one of their examples, the team drew a version of Jung Hee Kim's painting Sae-Han-Do, of a house and trees. While the whole painting looked like a silver drawing, it actually wired an LED to a five-volt battery, literally lighting the painting up. [Science Daily]